Field of the Invention
The present invention relates to an inspection apparatus which scans an object to be inspected with light to obtain data of the object, a method for controlling the inspection apparatus, and a program.
Description of the Related Art
As one of inspection apparatuses, a scanning laser ophthalmoscope (SLO) is currently applied to obtain data such as images of an eye to be inspected. An ophthalmic imaging apparatus (one aspect of the inspection apparatus) typified by the SLO uses a scanning optical system including two kinds of scanners to perform a 2D scan of the eye to be inspected with illumination light, thereby obtaining an image. In this event, the apparatus typically uses a resonant scanner (resonance type scanner) in a main scanning direction of the 2D scan and a galvano scanner in a sub-scanning direction.
Such an ophthalmic imaging apparatus typified by the SLO has recently been required to have a higher resolution. At the same time, the ophthalmic imaging apparatus has been required to achieve a higher frame rate and a higher refresh rate throughout operations from data acquisition to image generation for the purpose of enabling a good diagnosis of an eye to be inspected, and also to provide a high-resolution less distorted image for use in actually inspecting the eye fundus in detail. A configuration disclosed in Japanese Patent Application Laid-Open No. 2014-68703, including a resonant scanner and a galvano scanner, accomplishes a higher resolution by performing reciprocating scanning with the resonant scanner to increase the number of pixels captured in one frame.
Meanwhile, as for a deviation between the data acquisition position on the eye fundus and the corresponding pixel on the display screen to be described later, two pieces of data acquired at two positions on a sub-scanning line are used for calculation to obtain data of a pixel which is located at a middle position between the two data acquisition positions and has no corresponding data. This eliminates the necessity to consider the displacement between the data acquisition position and the corresponding pixel, and provides an image with no distortion.
Here, the reciprocating scanning means acquisition of information in both of forward scanning and backward scanning during scanning with the illumination light moved in the main scanning direction. Also, a higher frame rate means an increase in frame rate expressed by the number of frames per unit time at which one image to be displayed on a display screen is generated from data. A higher refresh rate means an increase in refresh rate equivalent to a replacement speed in continuous display of images on the display screen as a moving image, for example, at which a first image for one timing is replaced by a second image for the next timing.
The eye to be inspected repeats motion called involuntary eye movement. Thus, for image acquisition, it is required to detect the involuntary eye movement of the eye to be inspected and to perform eye fundus tracking which is to correct the scanning position of the illumination light in response to the involuntary eye movement. In this event, in order to quickly respond to the involuntary eye movement, it is important to improve the responsiveness of the eye fundus tracking by improving the frame rate and the refresh rate. Moreover, actual inspection also requires provision of a moving image with less flicker and good visibility. From this viewpoint, again, there are needs for a higher frame rate and a higher refresh rate in data acquisition for image generation and in the image generation.
Note that, as described above, the ophthalmic imaging apparatus often performs scanning with the illumination light in the main scanning direction with the resonant scanner and performs scanning with the illumination light in the sub-scanning direction with the galvano scanner. As described in Japanese Patent Application Laid-Open No. 2014-68703, it is required to also pay attention to image distortion for improving the resolution by the reciprocating scanning with the resonant scanner. Therefore, in order for an inspector to perform inspection without feeling strangeness during observation of an eye fundus image, data acquisition of the object to be inspected such as the eye fundus is required to improve the visibility of an image against the distortion.
Moreover, the configuration disclosed in Japanese Patent Application Laid-Open No. 2014-68703 makes no mention of the interlaced scanning. Therefore, there is also no suggestion about point to note in generation of images from data acquired by the interlaced scanning. As a measure against the deviation between the data acquisition position and the corresponding pixel described above, the technology disclosed in Japanese Patent Application Laid-Open No. 2014-68703 uses data at two data acquisition positions at an equal distance in the sub-scanning direction from the location of the pixel for which the data is to be calculated. Thus, when the distance between the two pieces of data is increased, the obtained data of the pixel may fail to reflect an actual state, and result in generation of a so-called blurred image.